1. Field of the Invention
The present invention relates to a fiberboard used as an automobile interior material or building material and its producing method.
2. Detailed Description of the Prior Art
A fiberboard formed by hot-pressing a fiber-layered product obtained by mixing thermoplastic fiber with a fibrous material is used as an automobile interior material such as a door-trim base material, inner panel, pillar garnish, rear package, ceiling base material, shock absorber or acoustic material, or as a building material such as a wall material, floor material, shock absorber under-floor or heat insulator.
Moreover, a fiberboard made by mixing natural fiber with cellulose biodegradable plastic is disclosed (refer to, for example, Japanese Patent Laid-Open No. 2000-127117) as a fiberboard having biodegradability with a view to reduction of the environmental load, given the recent emergence of global environmental problems, on final disposal.
However, with the cellulose biodegradable plastic there exists a problem in that it requires much solvent, resulting in a considerable degree of influence on the environment, at the producing stage. This type of the solvent includes alkaline solvent used in a process for isolating cellulose from a plant, dimethylacetamide, dimethyl sulfoxide or N-methyl morpholine-N-oxide used for synthesizing cellulose derivative, and carbon disulfide or methylene chloride used for fibrosing the plasatic.
Though the cellulose biodegradable plastic is non-petroleum biodegradable plastic, much petroleum solvent is used in its manufacturing process. Therefore, it is a problem that the cellulose biodegradable plastic greatly influences the environment when all stages of producing, use, and final disposal of a fiberboard using the cellulose biodegradable plastic are considered.